Civil Engineering: Grand design, low carbon

Nottingham University investigates energy-saving methods and materials for new-build homes

category/civil engineering
winner/creative energy homes/university of nottingham/
tarmac and other partners

Reducing the energy we use in our homes is one of the major planks of climate change reduction policy and normally this is presented as being connected to changes in behaviour: switch off your lights, defrost the fridge regularly and so on. But how can homes themselves contribute to energy saving? What house-building methods and materials are best for reducing energy use, and can these techniques be applied to existing buildings?

The Creative Energy Homes project is Nottingham University’s attempt to answer these questions. Led by Prof Saffa Riffat, head of the Institute of Sustainable Technology at the Department of the Built Environment, the project brought together companies across the house-building sector to investigate the problem in the most direct way – by building houses.

Legislation is an important driver for the project, with the government’s Code for Sustainable Homes target to make all new homes zero carbon by 2016. ‘There have been a number of attempts at building zero-carbon properties but they’ve all been fairly “Grand Designs”, usually expensive,’ said Darren Waters, head of the commercial division of Tarmac, one of the companies involved in the project. ‘We had three guiding principles: the design should be simple, affordable and repeatable.’

Riffat explained that he had been interested in low-carbon homes since 2000. ‘We already had a track record in the field from building an eco house on the campus. That had been very successful in terms of student training and encouraging commercial firms to visit the campus. Because of the success of that house, I went to the university and asked them to give us some land, which allowed us to interest people in the construction industry in this field.’

The university was happy to oblige and, over the next few years, companies became interested and joined the scheme. More than 120 companies have now contributed by supplying equipment or materials, co-funding the project, or building a house themselves. All of the £2.5m cost of the project was provided by industry.

There are now six houses on the site. Tarmac built a pair of semi-detached houses, one to Level 6 of the Code (zero carbon) and the other to Level 4 (a 44 per cent improvement on the previous Building Code). These are intended to prove that houses built using traditional masonry and techniques can perform as well as those made of wood or more exotic materials.

Civil engineering firm Roger Bullivant opted for a house that was designed to cost no more than £60,000, which incorporates lightweight concrete panels and a combination of ground-source heat pumps and thermal-energy storage. BASF was interested in its Smart Board material that contains encapsulated waxes that melt in warm weather and resolidify when cool, increasing the thermal mass of the house and reducing summer overheating. The company has built a ‘solar passive’ house using these.

The Steel Research House uses a steel frame – fabricated off site – for support and incorporates a range of renewable technologies and water-saving and energy-efficient systems. E.On chose to build a 1930s-style house, mimicking a large proportion of the existing housing in the UK, to see whether adding various modifications such as double glazing, higher-efficiency insulation and other energy systems can bring the performance up to Level 6 standard.

‘Each company has its own interest but we have input to make our own suggestions in terms of the architecture, the design and so on,’ Riffat said. ‘We have architecture, planning, sustainable technologies and building services within the school of the built environment, and we use the houses to train our students. PhD and Masters students helped with the construction.’

Riffat’s group analysed the houses’ performance using sensor systems spread throughout the buildings. ‘Some of the houses have 300 sensors looking at temperature, humidity, energy use and occupancy. We also look at how people behave in the houses.’

For Tarmac, the project was a chance to dispel sustainable-housing myths. ‘It’s often said that the only way to meet the higher levels of the new Code is to build in lightweight materials such as timber,’ said Waters. ‘We believe that masonry offers significant performance over timber. Nobody counts the carbon cost of importing wood from Scandinavia or Canada, which is where 90 per cent of the timber in the UK comes from. The icing on the cake is that masonry is cheaper to build with.’

“There were three design principles: simple, affordable and repeatable”
DARREN WATERS, TARMAC

In the UK, Waters said, it’s important to get the right mix of building technology and environmental gadgetry. ‘As UK temperatures rise you need to have the building envelope right and the rest is about renewables such as biomass boilers, solar hot water, ground-source heat pumps and so on. The only difference between our Code 4 and Code 6 houses is that the Code 6 has photovoltaic panels on the roof.’

For Riffat, the project represents a way to share knowledge and inspiration with the commercial sector. ‘It’s really a combination of their ideas and ours,’ he said.

The E.On 1930s house is likely to be the most immediately successful, Riffat believes. The recession has put many new-build projects on the back burner but there are still millions of houses in the UK whose energy performance could be improved. ‘We’ve won some funding from the Technology Strategy Board and we have a consortium with Nottingham City Council to roll out some of the innovations in a number of houses in the city,’ he said. Nottingham has secured a £260m grant to regenerate the Meadows area of the city, including bringing the housing there to a better standard of energy efficiency. ‘We have a good dialogue going on with the council and our experience with the E.On house is an important part of this. But it’s difficult – impossible, really – to do this without the support of the government. We have one more plot on the site, which we’ll allocate to another company, but as people start building again, the designs will come into their own.’

Runners up

Civil engineering
The other shortlisted candidates in this category were:

FIBRE-OPTIC HEALTH MONITORING
BAE Systems Advanced Technology Centre, Smart Fibres, Insensys, Aston University

Efforts within the aerospace sector to devise a way of monitoring the structural integrity of components made from composite materials has led to commercial spin offs. BAE and Aston developed optoelectronic instruments to measure strain within composite materials; the two spin-off companies, Smart Fibres and Insensys, respectively provide systems for monitoring large structures and the blades of wind turbines.

DSP FOR BURIED CABLE DETECTION
Cable Detection, University of Staffordshire

This project uses digital-signal processing to improve the sensors that detect underground cables and piping. As well as allowing Cable Detection a technological edge to compete against larger companies, this has led to a demonstrator project for nuclear-decommissioning applications at Sellafield and another to monitor oil and gas pipelines offshore.